Gentamicin

Indications

• • septicaemia and neonatal sepsis

  • meningitis and other CNS infections

  • biliary-tract infection

  • acute pyelonephritis or prostatitis

  • endocarditis

  • pneumonia in hospital patients

  • adjunct in listerial meningitis

Administration/Absorption

• intravenously

• intramuscularly

• topically

Dosage

Distribution

• • binds avidly to certain tissues.

Mechanism

• • vs Gram-negative organisms

  • Several potential antibiotic mechanisms, some as protein synthesis inhibitors, although their exact mechanism of action is not fully known:

    • Interfere with the proofreading process, causing increased rate of error in synthesis with premature termination.^[3]

    • Evidence of inhibition of ribosomal translocation where the peptidyl-tRNA moves from the A-site to the P-site.^[3]

    • Can also disrupt the integrity of bacterial cell membrane.^[4]

  • Bind to the bacterial 30S ribosomal subunit^[5][6] (some work by binding to the 50S subunit^[7])

Excretion

• • Completely eliminated unchanged in the urine

Side effects

• nephrotoxicity

  • gentamicin toxicity:

    • Balance difficulty

    • Bouncing, unsteady vision

    • Ringing in the ears

    • Difficulty multi-tasking, particularly when standing

Interactions

Contraindications

• • Neisseria gonorrhoeae, Neisseria meningitidis, Legionella pneumophila

    • risk of the patient going into shock from lipid A endotoxin found in certain Gram-negative organisms